Dog Tips

Itchy Pets? Here's What You Should Know About Histamines

Your pet's body needs it, but when it goes into overdrive, it can trigger a host of unpleasant symptoms, including itching, skin redness, and breathing problems. Here's what to do to help your pet feel better.

Reviewed by Dr. Arielle Walton

May 14, 2025 • 5 min read

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STORY AT-A-GLANCE

Persistent itching, digestive upset, and anxious behavior in pets could point to histamine intolerance — a hidden cause that many overlook when allergies and diet changes don't solve the problem
Histamine is a natural chemical that helps defend your pet’s body, but when it builds up too much, it can trigger itching, gut issues, breathing problems, and even behavior changes
Gut damage, liver overload, certain medications, environmental allergens, and chronic stress can block your pet’s ability to break down histamine properly, making symptoms persist despite regular treatments
High-histamine foods, such as aged cheeses, processed meats, fermented products, and certain types of fish, can worsen symptoms. In contrast, fresh meats, simple grains, and low-histamine fruits offer safer options
Healing your pet’s gut, supporting their liver, reducing environmental triggers, and managing stress naturally are key steps to restoring their health and easing chronic histamine-related discomfort

If your pet is constantly scratching, has an upset stomach, or even seems extra anxious, you might be wondering what’s going on. You’ve changed food, you’ve tried medications, and maybe you’ve even ruled out allergies — yet the problem continues.

These symptoms are a common problem among pet owners, and the mystery can be frustrating. What you might not realize is that there’s a hidden reason behind these stubborn symptoms — histamine intolerance (HIT), also known as enteral histaminosis. While it might sound complicated, don’t worry. There are steps you can take to help your furry friend feel better naturally.

What Is Histamine, Anyway?

Histamine is a natural part of your pet’s body. As an article from My Pet Nutritionist explains, "Histamine is a transmitter in the nervous system and a signaling molecule in the gut, skin, and immune system. Histamine is synthesised from the amino acid histidine, which is an essential amino acid for humans and dogs."¹

Histamine plays an essential role in your immune, digestive, and nervous systems. Think of it as your pet’s emergency alarm system — when their body spots something it thinks is dangerous, such as pollen, dust, mold, or certain foods, histamine gets released as a first line of defense. Some of histamine’s uses include:

Fighting infections and allergens
Moving food through the gut
Sending messages between different parts of the body

In small amounts, histamine is helpful. It keeps your pet safe and healthy. However, when histamine levels become elevated, they can lead to allergic reactions and discomfort, triggering symptoms like:²

Constant itching — Especially around the paws, ears, belly, or tail
Skin redness and swelling — Sometimes these can lead to sores or hot spots
Upset stomach — Diarrhea, vomiting, bloating, or excessive gas
Breathing troubles — Coughing, sneezing, or wheezing
Behavior changes — Hyperactivity, anxiety, or seeming "on edge."

When these symptoms recur frequently and regular treatments don’t seem to help, histamine intolerance may be the hidden cause.

Why Do Some Pets Have Trouble with Histamine?

So, if histamine is natural, why is it causing problems in your pet? The answer lies in an enzyme called diamine oxidase (DAO). This enzyme acts like a cleanup crew that breaks down and cleans out histamine, making sure it doesn’t build up to dangerous levels.

But sometimes, the enzyme doesn’t function properly, leading to enzyme overload. There are some reasons why this happens, such as:³

Gut Issues — Your pet’s gut is the first line of defense against histamine overload, but if their gut lining is damaged — a problem called leaky gut — histamine can slip into the bloodstream too easily. What’s more, it can also produce more histamine, making the situation worse.
Liver overload — Your pet’s liver is like a massive filter that cleans the blood. Part of its job is breaking down leftover histamine. But when the liver is overwhelmed by toxins, like medications, environmental chemicals, or poor-quality foods, it struggles to keep up.
DAO blockers — Some medications and even certain vitamin supplements can block DAO activity. If DAO isn’t working correctly, histamine doesn’t get broken down. Common DAO-blocking medications include antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, muscle relaxants, and antifungals.⁴ If your pet has been on long-term medications, this could be playing a significant role.
Environmental triggers — Even if you feed your pet the perfect food, their environment might still be pushing histamine levels too high. Common environmental histamine triggers include pollen, mold spores, dust mites, household cleaners, air fresheners, and sprays. When your pet breathes these in every day, their body reacts by releasing more and more histamine.
Stress — Constant stress can severely affect their immune system, as it throws off hormone levels like cortisol. The imbalance can increase histamine production and make their body less able to deal with it. Common triggers include changes in routines, separation anxiety, and too much or too little exercise.

Certain Foods Can Make Histamine Problems Worse

Some foods naturally contain high levels of histamines, while others can trigger your pet’s body to release additional histamines. My Pet Nutritionist explains that "microbiologically altered" foods are one example, as manufacturers may have processed them in unhygienic conditions. Fermented foods are another, as the bacteria during the fermentation process may have aminogenic properties.⁵

Even foods that are considered healthy can be problematic if your pet struggles with histamine. If your pet is showing symptoms of HIT, avoid feeding them these high-histamine foods:⁶

Aged cheeses like cheddar, parmesan, and gouda
Processed meats like bacon, pepperoni, and sausages
Fermented foods like kefir, yogurt and sauerkraut
Certain fish (tuna, sardines, and mackerel, especially if not super fresh)
Shellfish — shrimp, prawns, and mussels are high in histamine
Vinegar and vinegar-based products like pickles, ketchup, and salad dressings
Certain vegetables like tomatoes, spinach, and eggplant

The good news is that there are plenty of safe, delicious foods for your pet. Some low-histamine foods you can feed them include:

Fresh meats like turkey, lamb, and bison
Non-fermented vegetables like carrots, zucchini, broccoli, and cucumber
Low-histamine fruits like apples, pears, and blueberries

When possible, use fresh ingredients and prepare meals at home to avoid hidden additives and preservatives. Freshness is key; the longer food sits around, the more histamine builds up.

How to Help Your Pet Heal Naturally

If you suspect your pet is struggling with histamine intolerance, it’s best to consult with your integrative vet to help you come up with a diet plan for your pet. You may also need to work with a canine nutritionist to do an elimination diet. Make sure to monitor their symptoms and triggers (one way to do this is to keep a journal) so you can avoid them in the future.⁷

To manage histamine’s effects, one of the most important things to do is to heal the gut. Some strategies include:⁸

Giving your pet probiotics — Strains like Lactobacillus rhamnosus and Bifidobacterium longum help your gut heal without producing extra histamine.
Trying peptide therapy — Specialized peptides like BPC-157 and KPV help speed up gut healing and reduce inflammation.
Using gut-healing herbs — Slippery elm coats and soothes the gut lining, while marshmallow root reduces inflammation and supports gut repair. Turmeric is another beneficial spice with natural anti-inflammatory properties that support gut health.

Supporting your pet’s liver is also essential, as it detoxifies histamine. If your pet’s liver isn’t functioning properly, toxins and histamine can build up. One way to do this is by avoiding unnecessary medications whenever possible.

Reducing your pet’s stress and anxiety is also crucial. Keep a consistent daily routine, and provide quiet, cozy spaces where your pet can relax. A calm pet heals faster and handles histamine better.

Lastly, reduce your pet’s histamine triggers by cleaning with natural, nontoxic products. Dust and vacuum regularly to remove allergens, and wash your pet’s bedding on a regular basis. Consider using a pet-safe air purifier, especially during allergy season.

Histamine Intolerance Is a Sign, Not the Root Problem

Histamine intolerance is not a disease — It’s your pet’s way of signaling that something deeper needs attention. By focusing on gut healing, liver support, reducing environmental triggers, lowering stress, and feeding your pet the right foods, you can help them heal naturally and truly thrive.